1. Technical Field
This invention relates generally to semiconductor device marking, and more particularly, to the prevention of counterfeit marking thereof.
2. Background Art
FIG. 1 illustrates a typically marked semiconductor device 20. As shown therein, the semiconductor device 20 includes a die 22 having a lid or transfer molding compound such as epoxy 24 thereon. A white layer 26, for example, a layer of white paint, is provided on the lid 24, and the black layer 28, for example black paint, is provided on the layer 26. A laser cutting step is undertaken to provide openings (one shown at 30) in the layer black 28 to the full depth thereof down to the white layer 26, to expose portions of the white layer 26. The formed openings 30 are patterned to provide information about the product, for example, the name and logo of the manufacturing company, the type of product, and so on, with the white layer 26 portions exposed by the laser cuts providing good visible contrast to the black material 28 thereabove.
With this structure, it is readily possible for a counterfeiter to provide counterfeit markings as illustrated in FIG. 24. Initially, the counterfeiter could grind away the entire black layer 28 and further into the white layer 26 (FIG. 2). Thereafter, the counterfeiter could provide another, new black layer 32 over the remaining white layer 26A (FIG. 3) and provide laser cuts into the black layer 32 to provide openings 30 therein which expose portions of the layer 26A, with the cuts providing openings as chosen to form counterfeit markings (FIG. 4). Viewing of such markings would provide no evidence of counterfeiting.
Therefore, what is needed is a system which thwarts a counterfeiter's attempt to remove proper markings from a semiconductor device and replace them with counterfeit markings.